Apparatus for filtering industrial liquids

ABSTRACT

An apparatus for filtering industrial processing liquids is disclosed which includes a tank, a continuous conveyor screen positioned in and defining a loop in the tank, and a continuous filter media placed on an outer surface of the conveyor. The apparatus includes a power operated tractor chain sludge elevator guidably mounted within the tank extending along and frictionally engaging an outer surface return portion of the filter media for effecting a positive upward lift movement of adjacent portions of the filter media with accumulated sludge thereon. The apparatus may also include an apertured horizontal partition in the tank, the filter media sealed over the aperture defining a filtered liquid reservoir chamber positioned below the partition and an unfiltered liquid chamber above the partition, an opened-top vacuum chamber sealed to the filter media and immersed within the filtered liquid chamber positioned within the aperture so as to form a peripheral channel between the aperture and vacuum chamber. An alternate embodiment of the invention includes an open top vacuum chamber with an unfiltered reservoir, a continuous sealing channel upon and surrounding the vacuum chamber, a filter media within the unfiltered reservoir and extending over and sealingly engaging the channel, the channel having a continuous slot in its top defining inner and outer sealing surfaces engaging the filter media. The channel in either embodiment may be connected to a positive or negative pressure source for discouraging the flow of unfiltered liquid into the vacuum chamber.

This is a divisional of co-pending application Ser. No. 07/338,944 filedon Apr. 17, 1989.

FIELD OF INVENTION

The present invention relates to a method of filtering industrialprocessing liquid and apparatus, and more particularly to the mountingof a disposable or continuous filter media so as to sealingly engage avacuum chamber within a filtration tank for the passage of filteredliquids therethrough.

BACKGROUND OF THE INVENTION

In the filtration of industrial processing liquids, such liquid passthrough a generally continuous filter media within a tank into a vacuumchamber having an outlet connected to a conduit which extends outwardlyof the tank and is adapted for connection to a pump for feeding filteredliquids back to a processing apparatus, for illustration. It is known inthe art that from time to time there is a build-up of debris and sludgeupon the filter media at the area where it covers the open-top inlet tothe vacuum chamber to such an extent that there is a greatly reducedflow of filtered liquids through the media and through the outlet of thevacuum chamber. Various automatic means are known based upon a vacuumbuild-up within the vacuum chamber such that when the vacuum reaches apreset value, a vacuum-responsive valve or switch operates a controlmechanism for effecting longitudinal feed of a filter screen which isguidably mounted within the tank for a simultaneous longitudinalincremental feed movement of the filter media such as to present a cleanfilter media to the open top inlet of the vacuum chamber. Normally, avacuum release valve functions initially to break the vacuum within thevacuum chamber and in a timed manner energizes the drive mechanism whichfeeds sprocket chains or the like for advancing the filter screen withthe filter media moving therewith.

SUMMARY OF THE INVENTION

An important feature of the present invention is to provide an improvedmethod and apparatus for moving the filter media using a tractor chainassembly which is mountable upon and along a return portion of thefilter media and adjacent screen so as to operatively engage portions ofthe filter media to provide a positive lifting advance thereoftransporting the filter media and accumulated sludge or debris thereonupwardly and out of the tank for disposal.

Previously, with sufficient loading of debris or sludge upon returnportions of the filter media, as it is being elevated from the tank, theweight is such that there is insufficient frictional drive between thepower-advanced supporting screen for the media and the media itself suchthat there is slippage, or alternately there may be such sufficientgrease accumulation upon the screen that the screen itself isineffective in elevating the sludge-accumulated media as it is advanced.

Previously, in the operation of industrial filtration apparatus for washliquids and the like, there has been contamination between theunfiltered liquids and the filtered liquids due to improper sealingbetween the filter media and the support thereof within the tank andwith respect to the vacuum chamber such that unfiltered liquids mayenter the vacuum chamber in an undesirable and unintentional manner.

As still another feature, various types of vacuum chamber isolationmechanisms are provided within the tank to provide an improved sealbetween the vacuum chamber and the filter media such as to excludeunwanted unfiltered liquid from entering into the vacuum chamber exceptfor passage through the filter media.

These and other features and objects will be seen from the followingspecification and claims in conjunctin with the appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevational and schematic diagram of one form of filterapparatus for industrial wash liquids incorporating an improved methodand apparatus for conveying the filter media.

FIG. 2 is a transverse fragmentary sectional view taken in the directionof arrows 2--2 of FIG. 1 illustrating the mounting of the chain-operatedfilter screen within a filtration tank including the filter media, andon an increased scale.

FIG. 3 is a similar view of the circled portion of FIG. 2, on anextended scale.

FIG. 4 is a fragmentary section taken in the direction of arrows 4--4 ofFIG. 2.

FIG. 5 is a fragmentary plan section taken in the direction of arrows5--5 of FIG. 2.

FIG. 6 is a schematic diagram of the modified filter apparatus.

FIG. 7 is a plan view thereof.

FIG. 8 is a schematic elevational view and diagram of a further modifiedfiltration apparatus.

FIG. 9 is a plan view thereof.

FIG. 10 is a schematic diagram of a first modification of the apparatusshown in FIG. 6.

FIG. 11 is a fragmentary section of the sealing channel of FIG. 8, on anincreased scale.

FIG. 12 is a schematic diagram of a second modified filtrationapparatus.

FIG. 13 is a schematic plan view thereof.

FIG. 14 is a schematic elevational diagram of a further modification ofthe filtration apparatus shown in FIG. 6.

It will be understood that the above schematic drawings are illustrativeof several embodiments of the invention, and of the method of filteringindustrial liquids, and other embodiments are contemplated within thescope of the claims hereafter set forth.

DETAILED DESCRIPTION OF AN OPERATIVE EMBODIMENT OF THE INVENTION

Referring to FIGS. 1 and 2, a vacuum-assisted filtration apparatus isgenerally indicated at 11 and includes a tank 13 with opposed side walls15. As is conventional, guideways 17 are mounted upon a pair of opposedwalls 15, FIG. 2, and include at their outer longitudinal edges acontinuous sealing bead 19.

A pair of opposed conveyor chains 21, FIG. 2, supportively mounted uponthe guides 17 and movable thereon include a series of upturned hooks 25adapted for positioning within longitudinally spaced grommets uponopposite longitudinal edges of the continuous conveyor screen 23, FIGS.1 and 2. The support and mount for the conveyor screen within the tankand driven by a pair of conveyor chains upon guides 17 is further shownin Applicant's assignee's U.S. Pat. No. 4,650,571 dated Mar. 17, 1987.To the extent that further detail is shown in that patent as to thestructure and mounting of the continuous screen and the drive therefor,such is incorporated by reference herein.

Just as in prior U.S. Pat. No. 4,650,571, there is herein therecognition that some automatic means are required reasonablyconventional in the art for providing incremental longitudinal advancesof the filter media 29 as it extends along the exterior of the conveyorscreen 23, FIG. 1.

In the illustrative embodiment, the present conveyor screen is connectedat its outer longitudinal edges to the respective conveyor chains 21 assupportably mounted upon the guides 17 adjacent opposed side walls 15 ofthe tank 13. The filter media 29 in the illustrative embodiment is about51 inches wide, corresponding to the distance between hooks 25 of theconveyor screen and is in frictional engagement therewith and for normalmovement therewith. The screen 23 extends over the sealing beads 19,FIG. 2.

FIG. 1 is essentially a diagram where a number of the elements are shownschematically including filter media roll 30. The filter media roll 30,supported and journaled as at 32, extends upwardly into operativeengagement with the underside portion of the filter screen 23 sometimesreferred to as the conveyor screen 23. Said screen upon its oppositesides is connected to opposite laterally spaced conveyor chains 21.These are supported upon and drivingly extend around the laterallyspaced drive sprockets 33 upon the motorized drive shaft 31. Thesprocket chains 21 follow the corresponding guides 17 upon the interioropposed walls tank 13 as continuous loops, fragmentarily shown in FIGS.1 and 2.

The elongated open-top vacuum chamber 35 is supported within tank 13 andnormally includes a peripheral sealing bead 19 at its open peripheralend adapted for cooperative registry with the continuous screen 23.

The filter media 29 which extends from the roll 30, and which in normaloperation is stationary, extends down towards the bottom of the tank andaround the exterior of the conveyor screen 23. The filter media 29 onits upward return sealingly bears against and covers the screen 23 whichcovers the open top and the corresponding sealing bead 19 around vacuumchamber 35. The filter media extends in a continuous manner to the topof FIG. 1 and dropping down as at 29 as spent media to a suitablecollection area 36, schematically shown. There is thus defined withintank 13 upon the exterior of filter media 29 a body of unfiltered liquid37 which is adapted to pass into vacuum chamber 35 and out through itsoutlet 39. Said outlet is connected to a conduit 43 and to apower-operated pump 41 for delivery to a parts processor 45, asschematically shown. Return dirty liquid from the processor drops backinto tank 13 as shown by the arrow in FIG. 1, into the unfiltered liquidreservoir 37.

Upon the undersurface of vacuum chamber 35 and communicating therewithis a vacuum release valve 49, schematically shown, and through a tube 51communicates with a valve operator 53. Under the condition of asubstantial build-up of sludge and debris upon the stationary filtermedia 29 where it overlies vacuum chamber 35, the flow of pumped liquidstherethrough and through the outlet 39 will be decreased to a verylimited extent. This creates a vacuum build-up upon the interior ofvacuum chamber 35. When the build-up reaches a present value, the vacuumrelease valve 49 is activated thereby controlling the valve operator 53.As is substantially conventional in vacuum-assisted filterationapparatus of the present type of apparatus, normally a solenoid opensthe normally closed valve 49 to break the vacuum within vacuum chamber35. After a short period through a timer, not shown, of approximately 5to 10 seconds, energizes the motor drive for the shaft 31, FIG. 1,driving the conveyor chains 21. These in turn effect a longitudinaladvance of the filter media 29 for a limited period such as 5 to 10seconds sufficient for the debris-cluttered portion of the media whichoverlies the entrant opening to the vacuum chamber to pass therefromupwardly. The drive for the sprocket drive shaft 31 is interrupted andfull flow of liquids from the unfiltered liquid chamber 37 can againflow into vacuum chamber 35. Some of the unfiltered liquid will passthrough adjacent exposed portions of the filter media upon the exteriorof the vacuum chamber such as to enter the clean liquid reservoir 71.

In the illustrative embodiment, the vacuum chamber 35 is shown asrectilinear in shape. It is contemplated that the length or dimension ofthe vacuum chamber could be increased so that there is a larger inletopening for unfiltered liquid for passing into the vacuum chamber andeventually through the outlet 39 and conduit 43 to the pump 41, FIG. 1.

Sometimes the filter media becomes so loaded with debris that there maybe some general slippage between the conveyor screen 23 and the filtermedia 29. Such slippage may also be caused because of some grease whichmay have gotten onto the conveyor screen or upon portions of the media.The intermittently movable conveyor screen 23 becomes less effective inelevating the filter media 29 to the extent it is loaded with debris fordisposal to the spent media area 36, such as shown schematically in FIG.1.

The present invention includes the method and apparatus by which thereis provided a tractor chain assembly sludge elevator generally indicatedat 55, FIG. 1. The tractor chain sludge elevator includes a pair oflaterally spaced continuous tractor chains 57, FIGS. 1 and 5, with aseries of longitudinally spaced transverse cross-frames 59. Therespective tractor chains are positioned partly within tank 13, FIG. 1,and project outwardly thereof and are arranged adjacent to and extendalong the return flight of the conveyor chains 21. Tractor chains 57engage corresponding drive sprockets 61, one of which is shown inFIG. 1. Said sprockets are secured upon drive shaft 63 and connected tothe corresponding conveyor screen drive sprocket 33 by the sprocketchain 65. The opposite end portion of the corresponding tractor chains57 extend around idler sprockets 67 journaled at 69 within tank 13.

The respective tractor chain assembly sludge elevator extends along andbears against the upper flight of the filter media 29 and is in positivefriction drive engagement with the adjacent longitudinally extendingconveyor screen 23. Thus, the present tractor chain assembly sludgeelevator provides an improved method for assisting in conveying thefilter media 29 using the tractor chains 57 and the correspondingcross-frames 59.

This provides for a positive upward movement of the filter media 29 andoperates in conjunction with some feed movement from the conveyor screen23.

The weight of the tractor chains 57 and their cross-frames 59 forcescontact of the filter media 29 relative to the carries or conveyorscreen 23 and the corresponding carrier screen sealing beads 19. Thisprovides for increased frictional lifting engagement by the tractorchain assembly 55 against and with respect to the return flight of thefilter media 29 and its adjacent conveyor screen 23.

In the previous discussion and wherein the operation of the valveoperator 53 first breaks the vacuum which had been established in thevacuum chamber 35, this has the effect of releasing the debris andparticles from the adjacent filter media 29 over vacuum chamber 35. Thetractor chain design includes the transverse cross-frames 59 which catchthe debris upon the filter media 29 which has been released therefromduring the vacuum release interval. The sludge elevator 55, 57effectively lifts such debris upwardly along with the simultaneousupward movement of the filter media 29 until the debris has travelledover the top to the assembly shown in FIG. 1 and drops down as at 29into the collection area for spent media shown at 36.

A modified vacuum-assisted filter machine as schematically shown at 75in FIGS. 6 and 7 and includes tank 77 and the horizontally disposedpartition 79 having a central elongated aperture 80, FIG. 7. Extendingfrom the media roll 30, FIG. 6 is the webbing or strip of filter media29 which extends around the pair of longitudinally spaced guides 81adjacent opposite ends of the aperture 80 so as to snugly overlieaperture 80, FIG. 7. The return extends over a corresponding take-uproll 85, normally under the control of the above-described conveyorscreen 23, such as shown in FIGS. 1-5.

Filter media 29 extends over the sealing beads 19 which extend along theedges and perimeter of the aperture 80 in the partition 79 to therebydefine with partition 79 the filtered liquid reservoir 83.

Elongated vacuum chamber 87 is immersed within filtered liquid reservoir83 and has an open top with a corresponding peripheral sealing bead 115thereon, FIG. 6, in engagement with the undersurface of the filter media29. Accordingly, filter media 29 extends over and operatively engagesthe peripheral seal 115 at the open side of the vacuum chamber 87 sothat unfiltered liquid 93 can pass through the filter media 29 and intothe vacuum chamber 87. For clarity, the conveyor screen 23 of FIGS. 1-5is omitted.

Vacuum chamber 87 is suitably supported within tank 77 as by thesupports 89. The flow of unfiltered liquid at 91 further passes throughthe media 29 and into the filtered liquid reservoir 83.

Vacuum chamber 87 has an outlet 95, sometimes referred to as a secondoutlet, in communication with the filtered liquid reservoir 83 withinwhich is nested a normally closed vacuum release valve 97.

The vacuum chamber 87 has a first outlet or pump outlet 99 connecting aconduit 101 which extends outwardly of the tank 77 for connection to amain flow pump 103 by which filtered liquids may be pumped an exteriorarea such as a procesor shown schematically in FIG. 1 and for subsequentreturn to the unfiltered liquid area 93 in FIG. 6.

One end of the vacuum chamber 87 is spaced from the partition aperture80 to define an elongated flow passage 105 for auxiliary filtered fluidsfrom the unfiltered liquid reservoir 93 into the filtered liquidreservoir 83, FIG. 6.

A return conduit 111 optionally redirects auxiliary flow of filteredliquids back into reservoir 93 for replenishing the liquids within thetank 77. Pump 109 (probably a jet pump) continuously removes reservoirliquid that may be contaminated by seal leakage.

The media seal 115, FIG. 6, extends around the periphery of the open endof the vacuum chamber 87 for cooperative sealing registry with filtermedia 29. Thus, an improved method is provided for maintaining a cleanliquid reservoir 83 for the vacuum release mechanism, namely the vacuumrelease valve 97, and wherein the filtered liquid reservoir 83 isinternal to the filter unit 75. This reservoir is usually outside thefilter tank and fed from a tap from the main pump.

The reservoir 93 is replenished through aperture partition edge 80 andvacuum chamber 87, even during use if desired. The reservoir 83 needs noexternal means of supply. In some situations, however, when the filteredfluids are delivered to a wash area, the accumulated fluids withparticulate therein are often returned to the unfiltered liquidreservoir 93.

Reservoir 83 thereby encompasses the vacuum chamber 87, therebyisolating it from the media seal 19 to seal the vacuum chamber againstany medial seal failures at 115.

The reservoir 83 may be optionally and continuously depleted with use ofthe auxiliary pump 109, conduit 108 and outlet 107 in order to removeany contaminant which may have been admitted during a media seal failureas at 115.

Vacuum release valve 97 is normally closed and is attached directly tothe vacuum chamber 87, FIG. 6, to eliminate piping and additional labor.Thus, the vacuum release valve is internal to the filter unit 75 toreduce the unit's exterior clearance dimensions. If during operation ofthe filter assembly 75 there is a build-up of sludge and debris upon thefilter media 29 at the open side of the vacuum chamber 87 sufficient tocause a reduction in the flow of filtered fluids therethrough, a vacuumwill build up in said vacuum chamber. When the vacuum reaches a presentlevel it will automatically open the vacuum release valve 97. This willhave the effect as above described of initially breaking the vacuumcondition within the vacuum chamber and secondly of energizing thefilter screen drive chain 21, FIG. 1, and the conveyor screen 23 such aswill advance the filter media sufficiently forward for a limited timeperiod as will present clean filter media 29 to the open intake side ofvacuum chamber 87.

A modified vacuum chamber isolation apparatus 119 is shown in FIGS. 8and 9 for use in conjunction with the vacuum-assisted filter machine121.

The construction is similar to what is shown in FIG. 6 except that thevacuum chamber 87 is supported at 89 within tank 77 and spaced belowfilter media 29. Continuous perimeter seal channel 123 is mounted uponand extends around the top of the vacuum chamber 87 and is suitablysecured thereto and functions as a filter media to vacuum chamber seal.Channel 123 is in operative engagement with the undersurface of thefilter media 29, FIG. 8, and/or conveyor screen 23, FIG. 1.

A continuous intermediate slot or opening 129 extends through the top ofthe perimeter seal channel 123 and defines upon its opposite sides acontinuous elongated inner seal surface 125 and the continuous outerseal surface 127, further shown in FIG. 11.

Optionally, the channel 123 may be used as a vacuum chamber perimeterseal as shown in FIG. 8. The opening of the channel faces the filtermedia 29 and presents two distinct seal surfaces 125, 127. The outerseal 127 prevents flow of unfiltered liquid into the channel 123. Theinner seal 125 prevents flow from the channel to the vacuum chamber 87.With the channel 123 being under negative pressure through the conduit108 through the tank wall 77 to the auxiliary pump 109, any unfilteredliquid that breaches the outer seal 127 can be withdrawn from the sealchannel 123 in an attempt to prevent it from breaching the inner channelseal 125 and thereby contaminating the interior of the vacuum chamber87.

In operation, the conduit 108 communicates with an auxiliary pump outlet107 for flow outwardly as shown by the arrow, FIG. 9, to the auxiliarypump 109.

With respect to the vacuum-assisted filter apparatus or machinedesignated schematically at 133 in the diagram, FIG. 10, channel 123 hasconnected thereto an inlet 137 which is connected to a diversion fromthe flow the main pump at 135, as schematically shown, to pressurize theinterior of channel 123. Thus, the above perimeter seal channel 123 mayoptionaly operate with a positive pressure with respect to theunfiltered liquid 93 in an attempt to discourage the unfiltered liquidfrom breaching the channel's outer seal 127.

A modified vacuum-assisted filter apparatus 139 is shown in FIG. 12illustrating a construction similar to the filtration apparatus shown inFIG. 6 and which includes the apertured partition 79 defining therebelowthe clean liquid reservoir 83 and thereabove the dirty or unfilteredliquid reservoir 93.

The vacuum-assisted filter apparatus 139, FIGS. 12 and 13, is similar tothat shown in FIG. 6, and the description of commonly identified partsis not repeated. The vacuum chamber 87 is positioned within thecorresponding elongated aperture 80 within the partition 79 so as todefine a peripheral channel 141 for filtered liquid which surrounds thevaccum chamber. In this variation of the vacuum-assisted filterapparatus, vacuum chamber 87 supported at 89 such that its edges engagethe overlying filter media 29 normally seals over the corresponding bead115 upon vacuum chamber. This provides a channel 141 surrounding vacuumchamber 87, FIG. 12.

Channel 141 contains filtered liquid 83 as it passes from the upperreservoir 93 of unfiltered liquid through the media 29 and through thecorresponding channel 141 down into the filtered media reservoir 83.

Pump 109 through conduit 108 and outlet 107 withdraws potentiallycontaminated liquid from reservoir 83.

The modified vacuum-assisted filter apparatus 143, FIG. 14, issubstantially the same as that shown in FIG. 12 except that instead ofwithdrawing liquids at 108 through the auxiliary pump 109, the filteredliquid reservoir 83 is pressurized by the delivery of pressurizedfiltered fluids through the conduit 135 from the main pump 103 throughfitting 145 back into the reservoir 83. This causes some upward movementof the filtered liquids through the surrounding peripheral channel 141around the vacuum chamber for the passage of fluid through the filtermedia 29 and into the unfiltered liquid chamber 93. This prevents entryof unfiltered liquid into vacuum chamber 87.

Having described my invention, reference should now be had to thefollowing claims.

I claim:
 1. In a filter apparatus for industrial process liquids, a tankreceiving and containing unfiltered liquids, a continuous conveyorscreen guidably mounted within the tank and projecting therefrom, theimprovement comprising:a continuous filter media overlying the tankguidably retained against said conveyor screen for horizontal movementwithin the tank and outwardly thereof; an open-top vacuum chambersupported within said tank underlying said filter media; a continuousperimeter seal channel overlying and surrounding said vacuum chamber andbearing against said filter media, said media spanning said sealedchannel; an outlet upon said vacuum chamber connected to a conduitextending from said tank connected to a pump for delivering filteredliquids to a process area; the top of the channel having a continuousslot therein defining elongated continuous inner and outer seal surfacesengaging said filter media; the outer seal surfaces preventing flow ofunfiltered liquid into the channel; the inner seal surfaces preventingflow from the channel into the vacuum chamber; said channel having alateral outlet connected to a conduit which extends from the tank, andis connected to an auxiliary pump, thereby providing a negative pressurewithin the channel, so that any unfiltered liquid that breaches theouter seal is withdrawn from the sealed channel to prevent it frombreaching the inner channel seal.
 2. In a filter apparatus forindustrial process liquids, a tank receiving and containing unfilteredliquids, a continuous conveyor screen guidably mounted within the tankand projecting therefrom, the improvement comprising:a continuous filtermedia overlying the tank guidably retained against said conveyor screenfor horizontal movement within the tank and outwardly thereof; anopen-top vacuum chamber supported within said tank underlying saidfilter media; a continuous perimeter seal channel overlying andsurrounding said vacuum chamber and bearing against said filter media,said media spanning said sealed channel; an outlet upon said vacuumchamber connected to a conduit extending from said tank connected to apump for delivering filtered liquids to a process area; the top of thechannel having a continuous slot therein defining elongated continuousinner and outer seal surfaces engaging said filter media; the outer sealsurfaces preventing flow of unfiltered liquid into the channel; theinner seal surfaces preventing flow from the channel into the vacuumchamber; said channel having a lateral outlet connected to a conduitwhich extends from the tank, and is connected to the outlet of said pumpfor pressurizing said channel with respect to the unfiltered liquidreservoir to prevent unfiltered liquid from breaching the channel outerseal.
 3. In a filter apparatus for industrial process liquids, a tank, acontinuous conveyor screen guidably mounted within the tank andprojecting therefrom, the improvement comprising:a horizontal partitionspanning the tank walls and having an elongated aperture therethrough;media sealing means upon the partition surrounding said aperture; acontinuous filter media overlying the tank guidably retained for sealingengagement with said sealing means, spanning said aperture andoperatively engaged by said conveyor screen; said filter media providingupon the underside of said partition an enclosed filtered liquidreservoir and upon its other side an open unfiltered liquid forreceiving unfiltered liquid; an elongated open-top vacuum chambersupported within said filtered liquid reservoir with its peripheral edgein sealing registry with said filter media and having a first outletconnected to a pump for delivering filtering liquid to a process area;longitudinally spaced guide means upon said tank guiding said filtermedia into cooperative engagement with the sealing means upon saidpartition and the open top of said vacuum chamber; a peripheral sealingbead around the open top of said vacuum chamber in registry with saidfilter media; said vacuum chamber being spaced within said partitionaperture defining a peripheral channel surrounding said vacuum chamberand filled with filtered liquid; an outlet conduit communicating withsaid channel, extending through said tank, and is connected to anauxiliary pump; and the sealing edges of said vacuum chamber relative tosaid filter media being surrounded by filtered liquid.
 4. In the filterapparatus of claim 3, further comprising said auxiliary pump creating areduced pressure within the filtered liquid chamber providing a flow offiltered liquid completely around the sealing edges of said vacuumchamber.
 5. In a filter apparatus for industrial process liquids, atank, a continuous conveyor screen guidably mounted within the tank andprojecting therefrom, the improvement comprising:a horizontal partitionspanning the tank walls and having an elongated aperture therethough;media sealing means upon the partition surrounding said aperture; acontinuous filter media overlying the tank guidably retained for sealingengagement with said sealing means, spanning said aperture andoperatively engaged by said conveyor screen; said filter media providingupon the underside of said partition an enclosed filtered liquidreservoir and upon its other side an open unfiltered liquid reservoirfor receiving unfiltered liquid; an elongated open-top vacuum chambersupported within said filtered liquid reservoir with its peripheral edgein sealing registry with said filter media and having a first outletconnected to a pump for delivering filtered liquid to a process area;longitudinally spaced guide means upon said tank guiding said filtermedia into cooperative engagement with the sealing means upon saidpartition and the open top of said vacuum chamber; a peripheral sealingbead around the open top the said vacuum chamber in registry with saidfilter media; said vacuum chamber being spaced within said partitionaperture defining a peripheral channel surrounding said vacuum chamberand filled with filtered liquid; and an outlet conduit communicatingwith said channel, extending through said tank, and is connected toprovide diverted flow from said pump and the diverted flow providing apositive pressure within the filtered liquid reservoir communicatingwith said channel for passage of filtered liquid into the unfilteredliquid reservoir for deflecting and discouraging unfiltered liquid frombreaching said media sealing means.